TWI804583B - Fuel supply system with improved carburetor for internal combustion engine, internal combustion engine and related motor vehicle - Google Patents

Abstract

A fuel supply system (4) for internal combustion engine (8) comprising: - a main supply conduit (12) provided with a throttle valve (16) of a carburetor (20) configured to provide an air/fuel mix to the engine (8); - an additional air conduit (28) provided with a second valve (32) configured to provide an additional portion of air to the internal combustion engine (8); - in which said second valve (32) is controlled by the pressure in the main supply conduit (12) downstream of said throttle valve (16) and/or by the position of said throttle valve (16).

Description

Fuel supply system with improved carburetor for internal combustion engines, internal combustion engines and related motor vehicles

The present invention relates to a fuel supply system with an improved carburetor for an internal combustion engine, an internal combustion engine comprising the fuel supply system and a related motor vehicle.

It is well known that internal combustion engines with carburetors, whether two-stroke or four-stroke, despite the use of catalyzers and specific spark advance mapping, are difficult to fine-tune and suffer from polluting emissions.

Pollutant emissions are particularly high in two-stroke internal combustion engines, especially in two-stroke internal combustion engines that do not have an active combustion chamber (quiescent combustion chamber), that is, there is no "squish" zone and it cannot be used off (cut-off) system, the oil will be suspended together with the oxidizing air.

The polluting emissions due to substantially unburned oil and hydrocarbons are particularly high in the release step of the accelerator. Precisely under these conditions, due to the absence of a shut-off valve, the carburetor allows the intake of fuel drawn by the depression generated by the piston, which is mixed with the lubricating oil.

Thus, an oil and fuel suspension can build up in an environment that is substantially devoid of or has little oxidizer (i.e., air), and this suspension is injected through the exhaust of an internal combustion engine, thus significantly increasing pollution. pollution emissions.

Furthermore, over time, unburned hydrocarbons and oils tend to contaminate the catalytic devices normally used upstream of the exhaust pipe, thus affecting or endangering their operation in all operating conditions and moreover increasing the polluting emissions of the internal combustion engine.

As shown, this phenomenon occurs especially during the gasoline-controlled release step, if, by closing suddenly, the throttle valve of the carburetor builds up a strong low pressure which attracts an increased amount of unburned fuel and oil to the combustion in the room.

To date, these disadvantages have been substantially resolved by switching the carburetor supply to one of electronic injection, which allows a quick and efficient cutoff in gasoline release conditions.

However, this solution increases the overall cost due to switching to a significantly more complex injection supply.

Therefore, there is no need to switch the carburetor to injection supply, and it is necessary to solve the disadvantages and limitations mentioned in reference to the prior art, so as to limit the cost and construction complexity of the fuel supply system of the internal combustion engine.

This need is met by a fuel supply system for an internal combustion engine according to claim 1, an internal combustion engine according to claim 12 and a motor vehicle according to claim 13.

4: Fuel supply system

8: Internal combustion engine, engine

12: Main Supply Conduit

16: Throttle valve

20: Vaporizer

24: Combustion chamber

26: Pump box

27: Main air filter

28: Extra Air Duct

29: Cylinder

32: Second valve

36: Air filter

40: branch conduit

44: Bypass conduit

48: Entrance

Further features and advantages of the present invention will be better understood through the description of the following preferred and non-limiting embodiments thereof, wherein: Fig. 1 shows a fuel supply system for an internal combustion engine according to a first embodiment of the present invention A schematic diagram.

Fig. 2 shows a schematic view of a fuel supply system for an internal combustion engine according to a second embodiment of the present invention.

The same elements or parts of elements in the embodiments described below will be denoted by the same numerals.

Referring to the above-mentioned figures, a general schematic diagram of a fuel supply system for an internal combustion engine 8 according to the invention is generally indicated at 4 .

For the purposes of this invention, it is worth noting that the term internal combustion engine is considered in a broad manner to include any engine type or configuration, including the Otto cycle and Both the Diesel cycle and the rotary engine (Wankel).

Furthermore, the type of engine has absolutely nothing to do with the type of vehicle on which the engine can be installed.

As stated, the specific advantages of a motor vehicle supplied with a carburetor are solved by the invention, characterized by a significant limitation of polluting emissions, but which in any case are still applicable in automobiles and in general in industry Vehicles and motor vehicles, engine generators, chain saws, lawn mowers and the like.

The term motorcycle means a sport motorcycle having at least two wheels, ie a front wheel and a rear wheel. Accordingly, three-wheeled motorcycles also fall within this definition, such as, for example, two pairs of guide wheels on the front axle and one drive wheel on the rear axle, and such motorcycles may also include One guide wheel on the front axle and two drive wheels on the rear axle. Finally, so-called quadricycles with two wheels on the front axle and two wheels on the rear axle fall within the definition of this motorcycle.

The fuel supply system 4 for an internal combustion engine 8 according to the invention comprises a main supply conduit 12 provided with a throttle valve 16 of a carburetor 20 configured to supply an air/fuel mixture to the internal combustion engine.

It is worth noting that the throttle valve 16 is intended to be any type of shut-off device suitable for adjusting the conduit width of the main supply conduit 12 in which the throttle valve 16 is inserted; A typical throttle valve 16 formed by a rotating plate-like element and further devices suitable for this purpose (such as, for example, guillotine valves, sector valves, etc.).

Furthermore, the concept of carburetor 20 is also intended in a broad manner to include any device that may be suitable for mixing a flow of air with a flow of fuel such as, for example, gasoline. Thus, the carburetor 20 can be of any shape and size, can be entirely mechanized or also provide autimatisms and electronic components for its adjustment.

The main supply conduit 12 is conveniently connected to the internal combustion engine 8; for example, as typically occurs with two-stroke engines, the main supply conduit 12 leads directly into a combustion chamber 24 and/or into a pumping tank 26, thereby supplying the internal combustion engine 8 at least one cylinder 29.

A main air filter 27 is preferably arranged above the main supply duct 12 upstream of the throttle valve 16 in a known manner.

The fuel supply system 4 further comprises an additional air duct 28 provided with a second valve 32 configured to provide an additional portion of air to the internal combustion engine 8 .

In particular, the air of the additional air duct 28 is delivered to the internal combustion engine 8 . According to a possible embodiment, the air of the additional air duct 28 can be fed into the crankcase chamber of the internal combustion engine 8 or also directly into the pump tank 26 .

As shown in FIG. 2 , the air in the additional air duct 28 can be mixed with air from the main supply duct 12 downstream of the throttle valve 16 and upstream of the input to the combustion chamber 24 .

For example, the additional air duct 28 can be connected to a part of the main supply duct 12 arranged downstream of the throttle valve 16 , whereby an additional air flow is delivered into the combustion chamber 24 .

Advantageously, the second valve 32 is controlled based on the pressure in the main supply conduit 12 downstream of the throttle valve 16 and/or by the position of the throttle valve 16 , as will be better explained subsequently.

It is worth noting that the expressions "downstream" and/or "upstream" that follow in the description are often considered with reference to the natural intake flow of air within the internal combustion engine 8; therefore, the "upstream" side is often on the air filter side or In any case on the air input side in the fuel supply system 4 , while the “downstream” side is often towards the side of the combustion chamber 24 and usually the side of the internal combustion engine 8 .

The additional air conduit 28 is provided with its own air filter 36 arranged upstream of the second valve 32 ; advantageously, the additional air conduit 28 is the main air filter 27 separate from the main supply conduit 12 . Due to this separation, the two conduits do not interact with each other from a hydrodynamic point of view. This allows the additional air conduit 28 to improve the operating conditions of the internal combustion engine 8 due to the fluid separation upstream between the main supply conduit 12 and the additional air conduit 28 , especially during the gasoline-controlled release step.

According to a possible embodiment, the second valve 32 is fluidly connected to the main supply conduit 12 via a sub-duct 40 , so that the pressure entering the main supply conduit 12 acts directly on the second valve 32 .

Preferably, for this purpose the second valve 32 is arranged close to the throttle valve 16 and the conduit 12 in order to minimize losses of load via the sub-duct 40 .

It is worth noting that the second valve 32 does not allow a direct exchange of air mass between the main supply conduit 12 and the additional air conduit 28 .

In other words, when the second valve 32 is also provided, the sub-duct 40 does not allow a direct exchange of air mass between the main supply duct 12 and the additional air duct 28, but only acts as a low pressure downstream of the throttle valve 16 via the sub-duct 40 ( In particular the latter (in the closed condition) can affect the second valve 32, thus causing the second valve 32 to open and thus allowing the passage of an additional air flow.

Thus, the second valve 32 may act as a vacuum valve controlled via a low pressure in the main supply conduit 12 and, for example, the second valve 32 may be a membrane valve.

As shown, the throttle valve 16 and the second valve 32 may be mechanically interconnected, thereby opening/closing the additional air conduit 28 depending on the position of the throttle valve 16 .

This mechanical connection results in no need for the sub-duct 40, however the sub-duct 40 can be retained to allow A dual control of the position of the second valve 32 .

In the case of a direct mechanical connection between the throttle valve 16 and the second valve 32, the operation of the second valve 32 is of a mechanical type, but in any case the second valve 32 is downstream relative to the throttle valve 16. The pressure in the main supply conduit 12. Specifically, the physical position of the throttle valve 16 in the main supply conduit 12 creates a corresponding pressure value downstream of the same throttle valve 16 .

Preferably, the fuel supply system 4 is calibrated such that when the throttle valve 16 is closed, the second valve 32 is opened to allow air flow, for example in the combustion chamber 24 with a titration of between 14.3 and 14.7 A mixture of air and fuel at titre.

According to a possible embodiment, the fuel supply system 4 comprises a bypass duct 44 branching off from the additional air duct 28 .

This bypass duct 44 allows the intake of yet another additional air flow which is not subjected to the action of the second valve 32 ; in other words, the branching of the bypass duct 44 takes place downstream of the second valve 32 . Thus, the air sucked in through the bypass duct 44 establishes a continuous, albeit limited, flow within the combustion chamber 24 which serves to dampen the pulsation of the internal combustion engine 8 .

An inlet 48 of the bypass conduit 44 can be connected to the main air filter 27 in turn, so as to receive the air filtered by the main air filter 27 .

In particular, a bypass conduit 44 connects the main air filter 27 to the main supply conduit 12 (FIG. 2) or connects the main air filter 27 to either the combustion chamber 24 or the pump box 26 (FIG. 1). Since the bypass duct 44 is a branch of the additional air duct 28 , the bypass duct 44 defines a direct passage between the main air filter 27 and the main supply duct 12 or between the main air filter 27 and the combustion chamber 24 . Thanks to this configuration, the bypass duct 44 allows a direct circulation of the air towards the internal combustion engine, which facilitates calibration in the event of failure of the second valve 32 or the throttle valve 16 .

Even at a reduced load, the above approach allows continuous operation of the internal combustion engine.

Constructively, the additional air duct 28 defines a sub-duct which cuts off the bypass duct. Tube 44. Thus, the bypass conduit 44 is separated from the second valve 32 provided along the additional air conduit 28 . In this way, the bypass conduit 44 is independent of the second valve 32 . In the event of failure of one or both of the valves, the air flow from the main air filter 27 flows directly into the bypass conduit 44 which blocks the main supply conduit 12 or the crank chamber so that the air flow supply to the internal combustion engine.

From what has been said it can be seen that the invention allows to overcome the disadvantages of the known art.

In particular, thanks to the use of the additional air duct 28, a suitable air flow can be provided to the internal combustion engine (also during the release step), thereby allowing the intake gas in the combustion chamber 24 or in the pumping tank 26 to be released during the release step of the accelerator. Combustion with oil.

The low pressure established in the combustion chamber 24 or pumping tank 26 creates a low pressure in the part of the main supply conduit 12 downstream of the throttle valve 16 . Although the throttle valve 16 is closed, this low pressure allows the opening of the second valve 32 , thereby allowing airflow to be input into the combustion chamber 24 or into the pumping tank 26 . Oxygen of the received air stream is thus combusted in combination with unburned hydrocarbons in the combustion chamber 24 or in the pumping tank 26 .

Thereby, the polluting emissions in all release steps of the accelerator are significantly reduced. Thereby, too large a catalyst (not shown) and its excessive overheating of the exhaust system can be avoided.

Under standard operating conditions of the internal combustion engine, ie at constant petrol and/or acceleration steps, the additional air duct 28 does not deliver any additional air flow and therefore does not modify the operating conditions of the internal combustion engine.

When a bypass duct is provided, the bypass duct not only provides an additional air flow to the internal combustion engine during the release step, but may often provide an additional air flow to the internal combustion engine.

This reduced extra flow serves to adjust the operation of the carburetor according to all operating conditions of the internal combustion engine, including boundary conditions such as temperature and atmospheric pressure. In other words, the extra air flow makes the carburetor less sensitive when the boundary conditions change, and thus makes the operation of the internal combustion engine more regular.

Thus, the present invention allows the catalyst to always be kept fed, ie correctly supplied, during the shut-off step of gasoline, thereby obtaining an efficient catalyst conversion.

Specifically, if the extra air flow interacts with the oil and fuel in the pump tank when the gasoline is turned off The fuel residue is mixed, and the combustion chamber remains active during the gasoline-controlled release step as long as the engine speed is no longer sufficient to generate a low pressure to keep the low-pressure (membrane) valve open.

Advantageously, the operation of the second valve, such as the low-pressure valve, is automatic but of the mechanical type, i.e. the second valve is managed naturally by the operation of the internal combustion engine, and therefore it does not require expensive and complicated operations/causes. motion control.

According to the low pressure naturally established in the main supply duct 12 after the throttling due to the throttling valve, and more easily by the mechanical connection between the rotation of the throttling valve and the position of the second valve, Automation can occur.

The result is a significant construction and adjustment simplification.

Advantageously, the main supply duct 12 and the additional air duct 28 do not draw air through the same filter box, but rather through two separate air supplies. In particular, the main supply duct 12 draws air through the main air filter, while the additional air duct draws air through its own second air filter. Thereby, the supply system of the air supplied via the main supply duct 12 is not affected by the pulsation of the internal combustion engine.

The fuel supply system of the present invention is affordable, enables and allows optimization of the operation of the carburetor, also in the release step of the accelerator, thus significantly reducing polluting emissions.

Those skilled in the art can make many changes and transformations to the above-mentioned fuel supply system and engine, all of which are included within the scope of the present invention defined by the appended patent claims.

4‧‧‧Fuel supply system

8‧‧‧internal combustion engine

12‧‧‧Main Supply Conduit

16‧‧‧Throttle valve

20‧‧‧Vaporizer

24‧‧‧combustion chamber

26‧‧‧Pump box

27‧‧‧Main Air Filter

28‧‧‧Extra air duct

29‧‧‧Cylinder

32‧‧‧Second valve

36‧‧‧air filter

40‧‧‧Sub-conduit

44‧‧‧Bypass conduit

48‧‧‧Entrance

Claims (13)

A fuel supply system (4) for an internal combustion engine (8), comprising: a main supply conduit (12), provided with a throttle valve (16) of a carburetor (20), configured to provide an air/fuel mixture to the internal combustion engine (8) a combustion chamber (24); an additional air conduit (28), provided with a second valve (32), configured to provide an additional portion of air to the internal combustion engine (8); wherein the second valve (32) is controlled by the pressure in the main supply conduit (12) downstream of the throttle valve (16) and/or by the position of the throttle valve (16); ) branched by a bypass conduit (44), wherein an inlet (48) of the bypass conduit (44) is connected to a main air filter (27), and an opposite end of the bypass conduit (44) is directly connected to the main supply duct (12) or the combustion chamber (24), causing the bypass duct (44) to establish a continuous air flow. The fuel supply system (4) for an internal combustion engine (8) as described in item 1 of the patent scope, wherein the main air filter (27) is arranged in the main supply conduit upstream of the throttle valve (16) ( 12) on. The fuel supply system (4) for an internal combustion engine (8) as described in claim 1, wherein the additional air duct (28) is provided with its own air filter (36), the air filter ( 36) is arranged upstream of the second valve (32). The fuel supply system (4) for an internal combustion engine (8) as described in claim 1, wherein the second valve (32) is fluidly connected to the main supply conduit (12) via a branch conduit (40) ), so that the pressure entering the main supply conduit (12) acts directly on the second valve (32). The fuel supply system (4) for an internal combustion engine (8) as described in claim 1, wherein the air of the additional air duct (28) is delivered to a crankcase chamber of the internal combustion engine (8) ( twenty four) among. The fuel supply system (4) for an internal combustion engine (8) as described in any one of claim 1, wherein the additional air duct (28) is connected to a valve arranged downstream of the throttle valve (16) A portion of the main supply conduit (12) whereby additional mass flow is delivered into the combustion chamber (24). The fuel supply system (4) for an internal combustion engine (8) as described in item 1 of the patent scope, wherein the second valve (32) is arranged at the throttle valve (16) and/or the main supply conduit ( 12) Nearby. The fuel supply system (4) for an internal combustion engine (8) as described in any one of claims 1 to 7 of the scope of application, wherein the second valve (32) is connected to the main supply conduit (12) A vacuum valve controlled by a low pressure. Such as the fuel supply system (4) for internal combustion engine (8) of claim 8, wherein the vacuum valve is a diaphragm valve, which does not allow the connection between the main supply conduit (12) and the additional air conduit ( 28) Direct exchange of air quality between. The fuel supply system (4) for an internal combustion engine (8) as described in claim 9, wherein the system is calibrated such that when the throttle valve (16) is closed, the second valve (32) is Open to allow an air flow, thereby obtaining a mixture of air and fuel with a titer between 14.3 and 14.7. The fuel supply system (4) for an internal combustion engine (8) as described in claim 9, wherein the second valve (32) is mechanically connected to the throttle valve (16), thereby according to the throttling The position of the valve (16) to open/close the extra air duct (28). An internal combustion engine (8), comprising a fuel supply system (4) as described in any one of items 1 to 11 of the scope of patent application, the fuel supply system (4) feeds at least one cylinder (29) of the internal combustion engine (8) ). A motor vehicle, including any one of items 1 to 11 in the scope of the patent application Described fuel supply system (4) and/or internal combustion engine (8) as the twelfth item of the patent scope.

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